The insertion/deletion polymorphism of the gene of angiotensin-converting enzyme (ACE) was investigated in a case-control study including 169 patients with suffering from either bipolar disorder type I or unipolar recurrent major depression (DSM-IV) and 169 healthy controls. No significant association was found with bipolar disorder type I or unipolar recurrent depression and the polymorphism of the ACE gene. A previously reported genetic association (Arinami et al., 1996) was not confirmed by the present study.